Issues with caching in threads

[MichaelHuth]

There are situation where we use the cache in threads and also WaveModCounterWrapper as part of determining the cache key that returns NaN in threads.

As WaveModCounterWrapper is not available might be not aware of wave modifications.

Another effect is that in the threads first accesses use the cache are uncached.

[t-b]

We could fallback to calculating the full wave hash in preemptive threads. But probably need a faster hash function for that. #2162